Aquatic Mercury Contamination

Biology and Molecular Biology Professor Meiyin Wu and Environmental Management doctoral candidate Natalie Sherwood are measuring the levels of mercury contamination in New Jersey’s aquatic ecosystems with the help of funding from the U.S. Geological Society and Rutgers University. Wu, the director of the Passaic River Institute, says the work ties into several ongoing research projects evaluating state waterways and the impact of human-induced pollution on the region’s aquatic flora and fauna.

Snapping turtles and the insects, fish, snails and algae they consume are a key focus of the study that will identify mercury transport pathways and accumulation levels in regional biota on the aquatic food chain.“The ultimate goal is to develop consumption advisory advice for those who eat the turtles,” explains Wu. “Turtle stew is considered a delicacy in parts of southern New Jersey.”

Mercury is present in aquatic habitats in its inorganic form, where it has been methylated by anaerobic bacteria to produce methylmercury. “Methylmercury is the form of mercury most easily absorbed and stored by organisms,” says Sherwood. People who eat contaminated food – especially seafood – risk ingesting high levels of methylmercury.

“Our intestinal tract absorbs up to 100 percent of the mercury consumed through food,” Sherwood says. “When ingested in high enough concentrations, it can act as a neurotoxin, first attacking the brain and the nervous system. Ingestion of mercury is most dangerous for pregnant women and young children.” Snapping turtles are long-lived omnivores with diets ranging from carrion and aquatic plants to fish and birds.

Because of their varied diet and longevity – 40-year lifespans are common – their meat has a potentially high concentration of mercury. “If consumed regularly, this could have significant human health implications,” Sherwood notes. Released by industrial processes such as coal-fired power plants, municipal waste combustion and steel and iron smelting, mercury is also a natural by-product of volcanic eruptions and forest fires. “We are looking at aquatic habitats from Flat Brook in Stokes State Forest and the New Jersey Meadowlands to Liberty State Park and all the way down to Cape May,” says Wu.